A portion of the exhaust gases produced by the combustion in the combustion chamber of an internal combustion engine is fed back to the subsequent combustion processes. This is carried out via an exhaust gas recirculation line and an exhaust gas recirculation valve adjustable via a control signal. The purpose of this device and of the method is to achieve the lowest possible emission values and minimize engine noise.
For implementing this method, an air mass sensor signal of an air mass sensor may be used.
In the case of a failure of the air mass sensor, an air mass replacement signal may be formed to mimic its behavior. In this approach, however, the exhaust gas recirculation valve must be closed. For example, this air mass replacement signal must be formed according to the so-called pTn process, which takes into account pressure, temperature and the speed of the internal combustion engine.
Furthermore, in the case of failures, which, for example, no longer allow a pTn process, it is possible to switch over to a so-called ‘limp-home’ method. In this connection, for the purpose of protecting the engine, the power of the internal combustion engine is greatly reduced with the exhaust gas recirculation valve also being closed.